Feasibility of Re-Plasticization of Plastic Explosive (PE-3A) for Ammunition

Abstract

Explosives and ammunition being the precious commodity require proper care and preservation while in storage and transportation. PE-3A is an RDX based plastic explosive manufactured by Pakistan Ordnance factory. PE-3A Composition hardens at low temperatures and has undesirable volatility and hygroscopicity characteristics, therefore, in-situ re-plasticization of PE-3A is required at Ordnance Depots where the explosives is being stored to avoid loss of resources, safety and security issues related with transportation and handling to circumvent its routine re-plasticization at POF. The major advantages of re-plasticization of the composition is to increase the stability, consistent output pressure in the form of explosion while demolition. As this plastic explosive is RDX based, being sensitive it can be initiated by shock, impact and friction, therefore RDX crystals are coated with the mixture of plasticizing oil and paraffin liquid in the presence of lecithin which helps to coat RDX crystals evenly. Carbon black is also added to retain the RDX crystals for homogenity of the composition. Almost all the cases requiring re-plasticization observed at POF occurred due to the loss of three ingredients i.e. lecithin, paraffin liquid and plasticizing oil. There are different methods of re-plasticization of PE-3A, one is conventional method which is in practice at Pakistan ordnance factory and cannot be adopted at Depot level as it is a full operational chemical plant and its commissioning and operational cost is very high. An alternate method has been devised in the present work while studying the whole process in Pakistan ordnance factory. The improvised method has been reported here comprises a mixer and rollers. Mixer is used to make the slurry of un-serviceable PE-3A through the addition of missing ingredients (Lecithin, Paraffin liquid and Plasticizing oil). Rollers are used to regain its plasticity, Rollers should be Teflon coated to avoid any unpleasant incident. Mixer thus designed can handle seven kilogram batch of explosive for reiii plasticization at ammunition depot at a time. The upshot of this work is that a viable alternate technique for in-situ re-plasticization of PE-3A has been developed with low cost.